Electrostatic flocking apparatus



June 4, 1968 A. WIRTH 3,386,416

ELECTROSTATIC FLOCKING APPARATUS Filed Nov. 17, 1965 CAN BE UNEQ UALE 142 NONCONDUCTOR BRUSHES Fig.2.

INVENTOR:

ARNO H. WIRTH Attorney United States Patent 11 Claims. 01. 118-636) ABSTRACT OF THE DISCLOSURE An apparatus for electrostatic flocking onto the surface of a material whereby flocks form an adherent coating thereon. A flock supply container is provided with a permeable bottom in that a series of adjacent rollers fill a bottom opening formed therein. The rollers are each turned in a like rotational sense. Adjacent rollers engage each other elastically so that a uniform flow of flock migrates therebetween. This teaching achieves more uniform flocking than had been attainable by prior art devices. It is preferred that the rollers are brushes and that an electrical potential be maintained between the container and the article to be coated.

This disclosure concerns electrostatic flocking onto the surface of a material whereby flocks form an adherent coating thereon. The invention resides in an apparatus especially suitable to this task.

In prior installations flock was delivered from a supply container to the surface to be coated by (for example) round brushes through one or more sieves. To assure uniform flow these installations required considerable excess flock which resulted in superfluous flock reaching the surface to be coated.

Another approach involved brushing the flock from a supply band with the supply to the band subjected to control. The approach reduced surplus flock but distribution suffered. The deposition of flock became intermittent in that every brush movement caused a precipitation of flock whereupon a pause occurred until the next brush movement.

The present invention copes with the foregoing problems in a novel and facile manner. A flock supply container is provided with a permeable bottom in that a series of adjacent rollers fill a bottom opening. The rollers are each turned in a like rotational sense. Adjacent rollers engage each other elastically so that a uniform flow of flock migrates therebetween.

Basically this advance achieves more uniform flocking. Small lumps of flock are torn apart by the rollers as they elastically engage one another. This grinding action is particularly noticeable in a preferred embodiment wherein the rollers are cylindrical brushes with peripherally disposed bristles. The bristles of adjacent rollers engage one another in opposed linear motion. In another embodiment of the invention the rollers are made of a resilient material such as foam rubber.

Surplus flock is also reduced. In cleaning superfluous flock from the coated surface, extremely small losses are encountered.

As the flock is emitted by the rollers it comes (as usual) into a high-tension electrical field so that it is accelerated for attachment to the surface to be coated. Frequently this surface is prepared with an adhesive substance. The present invention improves adherence of flock onto the surface to be coated in that mechanical acceleration of the flock by the rollers offers a higher initial velocity on which the electrical acceleration can act. Where brush rollers are employed a throwing effect also results from the relaxation of deformed bristles as the flock is ejected.

The roller arrangement taught in this disclosure in- 3,386,416 Patented June 4, 1968 creases versatility of operation in that it lends itself to several convenient mechanical control techniques. Control can be exercised over the distance between adjacent rollers and the vertical positioning of the rollers; the entire series of rollers can also be tilted and roller sizes can be varied. By way of example apportioning flock to the rollers of a series can be modified by tilting the series and/or graduating the size of rollers along the series. Different ejection velocities can be achieved by changing roller sizes and/ or changing the angular velocity of some or all of the rollers. Using different sizes on rollers of a series can also be employed to reduce pile up of flock at one end of the supply container. These control techniques and combinations thereof can be chosen as different flocking requirements are encountered.

The above and other features will appear more fully from the following description viewed in conjunction with the accompanying drawing wherein like numerals are used throughout the figures and wherein:

FIGURE 1 is a diagrammatic sketch showing a section through an apparatus according to this invention.

FIGURE 2 is a sketch which indicates an apparatus wherein a series of rollers can be tilted.

FIGURE 3 is a simplified sketch similar to FIGURE 1 and showing a second series of rollers.

FIGURE 4 depicts an alternate roller arrangement wherein the rollers are made of a resilient material.

FIGURE 5 indicates the use of rollers having progressively increasing diameters.

As best seen in FIGURE 1 the basic arrangement of this apparatus includes track 1 adapted to position material 2 over which is disposed sieve electrode 3. Supply container 4 has cylindrical rollers 5 journalled for rotation and parallel to one another in a bottom opening. Catching plate 6 is mounted at the end of the series of rollers. In FIGURE 3 first series of rollers 7 is followed by a second series 8.

Viewing FIGURE 1 in greater detail material 2 is conveyed by means well known in the art and indicated by arrow 9 so that surface 10 to be coated is moved relative the upper portions of the assembly. It should be understood that material 2 could also be maintained stationary while the upper portions of the assembly are moved. Rollers 5 are journalled for rotation at hubs 11. The rollers are turned in a like rotational sense indicated by arrows 12 by means well known in the art. The angular velocities of rollers 5 need not be alike. These velocities could be changed by gear systems familiar to those skilled in mechanics. In the preferred embodiment each of the rollers 5 include brush elements 13 which project outward therefrom for elastic engagement with brush elements of adjacent rollers. Vertical and horizontal adjustments of rollers 5 can be accomplished by moving them up or down as indicated by arrows 14 or by moving them horizontally left or right as indicated by arrows 15.

Because of the like sense of rotation of all the rollers of a series it can occur with a horizontal series of rollers that the rearmost roller receives too little and the foremost roller too much flock. By inclining the base from position A of FIGURE 2 to position B (shown in dashed lines) a uniform flow of flock is achieved since superfluous flock of the foremost roller falls back due to gravity.

In an alternate arrangement shown in FIGURE 4 rollers 5 are made of a resilient material such as foam rubber.

Another alternate shown in FIGURE 5 has rollers 5 with progressively increasing diameters. By use of different roller diameters different peripheral speeds are introduced. Small rollers by virtue of their small peripheral speeds convey less flock than do larger rollers. By the arrangement shown in FIGURE 5 the accumulation of flock on the left wall of container 4 can be avoided.

Electrical potential plays an important role in assuring the adhesion of flock onto surface it}. Supply container 4 is maintained at a high voltage potential as indicated by source 16. Track 1 communicates surface 10 in contact with electrical ground 17. Sieve electrode 3 is maintained by source 18 at an electrical potential somewhat lower than that of supply container 4. Although sieve electrode 3 is not absolutely necessary, it improves uniformity of flock deposition. With sieve electrode 3 at a lower potential than container 4 a suction is imposed on descending flock.

In FIGURE 3 pan 19 is arranged in gap 26 above sieve electrode 3. Second series 8 of rollers is arranged next to each other in a second opening defined by pan 19. The rollers of second series 8 are arranged in similar fashion to those of first series 7. It is an object of this second series 8 of rollers to divide with certainty any small lumps passing between the rollers of first series 7. Source 2 maintains pan 19 at an electrical potential between that of container 4 and that of surface 10. If a sieve electrode 3 is employed then pan 19 Will be maintained at a potential between that of container 4 and sieve electrode 3. The rollers of second series 8 are preferably spaced farther apart than those of first series 7 so that falling flock leaves pan 19 rapidly. The ensuing mechanical acceleration is then supported by the electric field. It should be understood that sieve electrode 3 is used when the highest uniformity of flock distribution on surface It) is required. This sieve electrode serves as a suction electrode to prevent undesirable heaping of flock. Rollers of second series 8 are fabricated with metal brushes so that a uniform electrical potential is developed on all parts of pan 19. Brushes 11 on the rollers of first series 7 may (on the other hand) be made of an insulating material such as polyamidenitride or a polyurethane.

Those skilled in electrostatic flocking will understand that wide deviations may be made from the shown embodiment without departing from the main theme of invention defined by the claims. More particularly electrostatic flocking installations with a permeable bottom consisting of rotating rollers and with the conveyor direction substantially normal to the emission direction are contemplated. Thus flocking against gravity with decreased compressed air or voltage requirements could also serve as environments for this teaching as long as the flock is to be deposited on a flat surface.

What is claimed is:

1. An electrostatic flocking apparatus having a supply container for flock,

the container including a bottom which defines a first opening,

a first series of rollers arranged next to each other to substantially fill the first opening,

each of the rollers of the first series journalled for rotation,

means for turning each of the rollers of the first series in a like rotational sense,

adjacent rollers of the first series engaging each other elastically whereby a uniform flow of the flock migrates therebetween.

2. The electrostatic flocking apparatus of claim 1 with each of the rollers of the first series including brush elements which project outward therefrom for elastic engagement with the brush elements on at least one adjacent roller.

4 '3. The electrostatic flocking apparatus of claim 2 with an article having a surface on which flock is to be deposited and spaced below the container to define p,

means for providing relative movement between the container and the surface,

means for maintaining .an electrical potential across the gap. 4. The electrostatic flocking apparatus of claim 3 with a pan mounted in the gap, the pan defining a second opening, a second series of rollers arranged next to each other to substantially fill the second opening,

each of the rollers of the second series journalled for rotation,

means for turning each of the rollers of the second series in a like rotational sense,

means for maintaining the pan at an electrical potential between that of the container and that of the surface.

5. The electrostatic flocking apparatus of claim 4 with the pan made of metal,

each of the rollers of the second series including metallic brush elements projecting outward therefrom for elastic engagement with the brush elements of at least one adjacent roller.

6. The electrostatic flocking apparatus of claim 3 with a sieve electrode mounted in the gap,

means for maintaining the sieve electrode at an electrical potential less than that of the container.

7. The electrostatic flocking apparatus of claim 1 with each of the rollers of the first series made of a soft resilient material.

8. The electrostatic flocking apparatus of claim 3 with means for adjusting the distance between at least two adjacent rollers,

means for adjusting the vertical orientation of at least one of the rollers.

9. The electrostatic flocking apparatus of claim 3 with each of the rollers describing an axis disposed substantially parallel to axes of the other rollers in a common plane,

the bottom arranged to be rotatable about an axis in the common plane whereby the bottom is inclinable.

10. The electrostatic flocking apparatus of claim 3 with each of the rollers having dififerent diameters,

the rollers arranged according to progressive diameters.

11. The electrostatic flocking apparatus of claim 3 with the means for turning the rollers arranged to turn at least two of the rollers at different angular velocities.

References Cited UNITED STATES PATENTS 2,425,236 8/1947 Ferrante 118-308 x 2,603,383 7/1952 Wilson 222-414 X 2,742,018 4/1956 Lindquist 118-636 3,269,356 8/1966 Friderici 118-640 FOREIGN PATENTS 1,083,317 6/1954 France.

CHARLES A. WILLMUTH, Primary Examiner.

P. FELDMAN, Examiner. 

